Transmission device, transmission method, reception device, and reception method

ABSTRACT

There is provided a transmission device including: a transmission unit that transmits a container in a predetermined format including a first component stream that has, as component data, transmission video data obtained by switching between a plurality of types of transmission video data, and a predetermined number of second component streams that have pieces of other component data; and an information insertion unit that inserts dynamic range information of the component data that each of the component streams has into the component streams.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Priority PatentApplication JP 2015-208445 filed Oct. 22, 2015, the entire contents ofwhich are incorporated herein by reference.

TECHNICAL FIELD

The present technology relates to a transmission device, a transmissionmethod, a reception device, and a reception method, and particularly toa transmission device and the like for transmitting not only videostreams but also other streams having graphics data, subtitle data, andthe like.

BACKGROUND ART

There are cases in which standard dynamic range transmission video dataand high dynamic range transmission video data are mixed andtransmitted. Hereinafter, standard dynamic range will be referred to as“SDR” and high dynamic range will be referred to as “HDR” appropriately.In this case, the SDR transmission video data is data obtained byapplying an SDR opto-electrical transfer to SDR video data, and the HDRtransmission video data is data obtained by applying an HDRopto-electrical transfer to HDR video data. NPL 1, for example,describes an HDR opto-electrical transfer characteristic (a new gammacharacteristic) that includes a compatible area with an existingopto-electrical transfer characteristic (gamma characteristic)considering reception of an existing receiving device.

There is a possibility of switching of SDR transmission video data andHDR transmission video data occurring, for example, at timings ofprogram switching or insertion of commercials. When such switchingoccurs, it is necessary for a reception side to switch electro-opticaltransfer characteristics; however, an image disturbance occurs resultingfrom the switching, or display muting is performed to hide the imagedisturbance.

As an example in which an image disturbance can be distinctly perceived,there is graphics display through an operation of a so-called “d (databroadcasting) button,” which is provided as one of broadcastingservices. In this case, although graphics are superimposed over aprogram or a commercial, when an image displayed in a small window basedon video data is switched from SDR to the HDR or from HDR to SDR, achange occurs in color or brightness of the graphics display.

CITATION LIST Non Patent Literature

NPL 1: Tim Borer, “Non-Linear Opto-electrical Transfer Functions forHigh Dynamic Range Television,” Research & Development White Paper WHP283, July 2014

SUMMARY OF INVENTION Technical Problem

It is desirable for the present technology to satisfactorily prevent animage disturbance from occurring on a reception side when a plurality ofmixed types of transmission video data with different dynamic ranges aretransmitted.

Solution to Problem

A concept of the present technology is a transmission device including:

-   -   a transmission unit that transmits a container in a        predetermined format including a first component stream that        has, as component data, transmission video data obtained by        switching between a plurality of types of transmission video        data, and a predetermined number of second component streams        that have pieces of other component data; and    -   an information insertion unit that inserts dynamic range        information of the component data that each of the component        streams has into the component streams.

In an embodiment of the present technology, by a transmission unit, acontainer in a predetermined format including a first component streamthat has, as component data, transmission video data obtained byswitching between a plurality of types of transmission video data, and apredetermined number of second component streams that have pieces ofother component data is transmitted. For example, the predeterminednumber of second component streams may include a data broadcastingstream and/or a subtitle stream. By an information insertion unit,dynamic range information of the component data that each of thecomponent streams has is inserted into the component streams.

In an embodiment of the present technology described above, the dynamicrange information of the component data that each of the componentstreams has is inserted into the component streams. Thus, a receptionside can obtain output data by performing a luminance mapping process onthe component data based on its dynamic range information thereof tomatch display performance and performing compositing of the data.

In this case, because a characteristic of an electro-optical transferperformed on the output data can be fixed, an image disturbance causedby switching the electro-optical transfer characteristic can beprevented from occurring. When, for example, graphics are displayedalong with an image based on video data, even if the image based on thevideo data is switched from SDR to HDR or from HDR to SDR, no changeoccurs in color or brightness of the graphics display. In addition, inthis case, since the luminance mapping process is performed on thecomponent data to match display performance, display based on thecomponent data can be performed in a proper luminance state at alltimes.

Note that, in an embodiment of the present technology, for example, theinformation insertion unit may further insert color gamut information ofthe component data that each of the component streams has into thecomponent streams. In this case, the reception side can obtain outputdata by performing a color gamut conversion on the component data basedon its color gamut information to match display performance andperforming compositing on the data, and can perform display based on thecomponent data in a proper color state at all times.

In an embodiment of the present technology, for example, anotherinformation insertion unit that inserts identification informationindicating a type of transmission video data that the first componentstream included in the container has into a layer of the container sothat the identification information indicates a type of the transmissionvideo data after the switching from a timing a predetermined amount oftime or more earlier than a switching timing may be further included. Inthis case, the reception side can recognize the fact that the type ofthe transmission video data has been switched and further the type ofthe transmission video data after the switching from the timing apredetermined amount of time or more earlier than the switching timing.

Another concept of the present technology is a reception deviceincluding:

-   -   a reception unit that receives a container in a predetermined        format including a first component stream that has, as component        data, transmission video data obtained by switching between a        plurality of types of transmission video data, and a        predetermined number of second component streams that have        pieces of other component data; and    -   a processing unit that obtains output data by decoding each of        the component streams, thus obtaining a plurality of pieces of        component data, and then performing compositing of the obtained        plurality of pieces of component data,    -   Dynamic range information of the component data that each of the        component streams has is inserted into the component streams,        and    -   the processing unit obtains the output data by performing a        luminance mapping process on each piece of the component data        based on the dynamic range information of each piece of the        component data to match display performance, and then performing        compositing of the component data.

In an embodiment of the present technology, by a reception unit, acontainer in a predetermined format including a first component streamthat has, as component data, transmission video data obtained byswitching between a plurality of types of transmission video data, and apredetermined number of second component streams that have pieces ofother component data is received. Dynamic range information of thecomponent data that each of the component streams has is inserted intothe component streams.

The processing unit decodes each of the component streams to obtain aplurality of pieces of component data, and performs compositing on theplurality of pieces of component data to obtain output data. Theprocessing unit obtains the output data by performing a luminancemapping process on each piece of the component data based on its dynamicrange information to match display performance and performs compositingof the data.

In an embodiment of the present technology described above, each pieceof component data undergoes a luminance mapping process based on itsdynamic range information to match display performance and becomposited, and thereby output data is obtained. Thus, a characteristicof an electro-optical transfer performed on the output data can befixed, and occurrence of image disturbance caused by switching of theelectro-optical transfer characteristic can be prevented. In addition,display based on the component data can be performed in a properluminance state at all times.

In an embodiment of the present technology, for example, color gamutinformation of the component data that each of the component streams hasmay be inserted into the component streams, and the processing unit mayobtain the output data by performing a color gamut conversion process oneach piece of the component data based on the color gamut information ofeach piece of the component data to match display performance, and thenperforming compositing of the component data. In this case, displaybased on the component data can be performed in a proper color state atall times.

Advantageous Effects of Invention

According to an embodiment of the present technology, it is possible tosatisfactorily prevent an image disturbance from occurring at areception side when a plurality of mixed types of transmission videodata having different dynamic ranges are transmitted. Note that effectsdescribed in the present specification are merely illustrative and arenot limitative, and additional effects may be exhibited.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing an example of a configuration of atransmission and reception system as an embodiment.

FIG. 2 is a block diagram showing an example of a configuration of aservice transmission system.

FIG. 3 is a graph for describing opto-electrical transfercharacteristics.

FIG. 4 is a diagram for describing relations between switching timingsof transmission video data and insertion timings of identificationinformation for identifying transmission video data after switching.

FIG. 5 is a table showing an example of a structure of HDR videodescriptor.

FIG. 6 is a diagram showing content of principal information in theexample of the structure of the HDR video descriptor.

FIG. 7 is a table showing an example of a structure of an HDR subtitledescriptor.

FIG. 8 is a diagram showing an example of a structure of a MPEG-2transport stream.

FIG. 9 is a diagram showing an example of a structure of a transportstream of MMT.

FIG. 10 is a block diagram showing an example of a structure of aservice reception device.

FIG. 11 is a diagram showing an overview of a luminance mapping processwhen display performance is HDR.

FIG. 12 is a block diagram showing an example of a structure of a screencomposition processing unit when display performance is HDR and has awide color gamut.

FIG. 13 is a diagram for describing a configuration of a luminancemapping unit.

FIG. 14 is a diagram for describing the luminance mapping unit whendisplay performance is HDR and input transmission video data is SDRtransmission video data.

FIG. 15 is a diagram for describing the luminance mapping unit whendisplay performance is HDR and input transmission video data is HDRtransmission video data.

FIG. 16 is a diagram for describing the luminance mapping unit whendisplay performance is SDR and input transmission video data is HDRtransmission video data.

FIG. 17 is a diagram showing an example of graphics display through anoperation of a “d button” which is provided as one of broadcastingservices.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments for implementing the technology (hereinafterreferred to as “embodiments”) will be described. Note that thedescription will be provided in the following order.

1. Embodiment

2. Modified Example

1. Embodiment Configuration Example of a Transmission and ReceptionSystem

FIG. 1 shows a configuration example of a transmission and receptionsystem 10 as an embodiment. The transmission and reception system 10 isconstituted by a service transmission system 100 and a service receptiondevice 200. The service transmission system 100 generates an MPEG-2transport stream (TS) or a transport stream of MPEG media transport(MMT) (multiplexed stream) as a container, and puts the transport streamon a broadcasting wave or packets of a network to transmit the transportstream.

The transport stream includes a first component stream (a video stream)having transmission video data obtained by switching between a pluralityof types of transmission video data as component data and apredetermined number of second component streams having other componentdata. The predetermined number of second component streams include, forexample, a data service stream (a data broadcasting stream) and/or asubtitle stream, and particularly in the embodiment, include a databroadcasting stream and a subtitle stream. A data service stream has,for example, graphics data, image data, and the like as component data.A subtitle stream has subtitle data as component data.

Dynamic range information of component data that each component streamhas is inserted into the component stream. In addition, color gamutinformation of the component data that each component stream has isinserted into the component stream. Furthermore, identificationinformation indicating a type of transmission video data included in thetransport stream that the first component stream has is inserted intothe transport stream to indicate the type of transmission video dataafter the switching from a timing a predetermined amount of time or moreearlier than a switching timing.

The service reception device 200 receives the above-described transportstream (an MPEG-2 transport stream or a transport stream of MMT)transmitted from the service transmission system 100. The servicereception device 200 decodes each of the component streams to obtain aplurality of pieces of component data, and performs compositing on theplurality of obtained pieces of component data to obtain output data.

In this case, respective pieces of the component data undergo aluminance mapping process based on dynamic range information of thecomponent data to match display performance and compositing, and therebythe output data is obtained. Furthermore, in this embodiment, therespective pieces of the component data undergo a color gamut conversionprocess based on color gamut information of the component data to matchthe display performance and compositing, and thereby the output data isobtained.

The service reception device 200 obtains display image data byperforming an electro-optical transfer (to fix an electro-opticaltransfer characteristic) on the output data, and then performs imagedisplay based on this display image data.

Configuration Example of Service Transmission System

FIG. 2 shows a configuration example of the service transmission system100. This service transmission system 100 has a control unit 101, avideo encoder 102, a data service encoder 103, a still image encoder104, a subtitle encoder 105, a container encoder 106, and a transmissionunit 107.

The control unit 101 is configured to include a central processing unit(CPU) to control operations of the units of the service transmissionsystem 100 based on a control program. The video encoder 102 performsencoding, for example, MPEG4-AVC or HEVC on input transmission videodata to obtain encoded video data, and then generates a video stream VSas a component stream including the encoded video data. The video streamVS includes the transmission video data as component data.

The input transmission video data is obtained by switching between aplurality of types of transmission video data. The plurality of types oftransmission video data includes, for example, standard dynamic range(SDR) transmission video data and high dynamic range (HDR) transmissionvideo data. Here, the SDR transmission video data is obtained byapplying a SDR opto-electrical transfer to SDR video data. In addition,the HDR transmission video data is obtained by applying an HDRopto-electrical transfer to HDR video data.

FIG. 3 shows an example of so-called opto-electrical transfercharacteristics indicating characteristics of non-linear luminance codevalues that are used to transfer linear luminance of light in a physicalspace to a transmission space of a limited band. In this drawing, thehorizontal axis represents an input luminance level, and the verticalaxis represents a transmission code value. A curve a indicates anexample of an SDR opto-electrical transfer characteristic that isapplied to SDR video data having input luminance levels of 0 to 100%. Inaddition a curve b1 indicates an example of an HDR opto-electricaltransfer characteristic (an example compatible with the SDRopto-electrical transfer characteristic) that is applied to HDR videodata having input luminance levels of 0 to N*100%. The characteristic ofthis example coincides with the SDR opto-electrical transfercharacteristic up to a compatibility limit value of the input luminancelevel. When the input luminance level reaches the compatibility limitvalue, the transmission code value becomes a compatible level.

In addition, a curve b2 indicates an example of an HDR opto-electricaltransfer characteristic (an example not compatible with the SDRopto-electrical transfer characteristic) that is applied to HDR videodata having input luminance levels of 0 to N*100%. Furthermore, a curveb3 indicates an example of HDR opto-electrical transfer characteristic(an example not compatible with the SDR opto-electrical transfercharacteristic) having input luminance levels of 0 to M*100%. Here, Nand M are numbers greater than 1, and M<N. Note that, although M<N isset in this illustrated example, a relation of maximum luminance betweenb2 and b3 may be M>=N in general cases.

Returning to FIG. 2, the video encoder 102 receives input of dynamicrange information and color gamut information of the input transmissionvideo data. The video encoder 102 inserts the dynamic range informationand color gamut information into the video stream VS. Here, the dynamicrange information is information indicating an electro-optical transfercharacteristic corresponding to an opto-electrical transfercharacteristic that the transmission video data has (a transferfunction).

At this point, the video encoder 102 inserts meta information such asthe information indicating the electro-optical transfer characteristiccorresponding to the opto-electrical transfer characteristic that thetransmission video data has (the transfer function), the color gamutinformation of the transmission video data, information indicating areference level, and the like into a video usability information (VUI)region of an SPS NAL unit of an access unit (AU). In addition, the videoencoder 102 inserts an SEI message having the meta information such asthe information indicating the electro-optical transfer characteristiccorresponding to the opto-electrical transfer characteristic that thetransmission video data has (the transfer function) and the informationof the reference level into an “SEI” part of the access unit (AU).

Here, the reason for causing the SEI message to have the informationindicating the electro-optical transfer characteristic is that, when anHDR opto-electrical transfer characteristic is compatible with an SDRopto-electrical transfer characteristic even though transmission videodata is HDR transmission video data, information indicating anelectro-optical transfer characteristic corresponding to the SDRopto-electrical transfer characteristic (a gamma characteristic) isinserted into the VUI of the SPS NAL unit to help an existingSDR-responsive reception device to identify the characteristic, and thusin order for an HDR-responsive reception device to identify a video thatthe device received as HDR, information indicating an electro-opticaltransfer characteristic corresponding to the HDR opto-electricaltransfer characteristic is necessary at a location other than the VUI.

In addition, the reason for causing the SEI message to have thereference level information is that, when transmission video data V1 isSDR transmission video data, information indicating the electro-opticaltransfer characteristic corresponding to the SDR opto-electricaltransfer characteristic (the gamma characteristic) is inserted into theVUI of the SPS NAL unit, but there is no description on a standard forinsertion of the reference level.

In this case, the information indicating the electro-optical transfercharacteristic (the transfer function) represents an electro-opticaltransfer characteristic of, for example, “BT.709-5 transfer function(SDR),” “10-bit BT.2020 transfer function (SDR),” “SMPTE 2084 transferfunction (HDR1),” “HDR (HDR2),” or the like. Note that “HDR (HDR2)” is atransfer characteristic partially having the same kind of characteristicas the gamma characteristic from the past, rather than a characteristicsupporting a “human visual system.” In addition, the color gamutinformation represents a color gamut of “BT.709-5,” “BT.2020,” or “SMPTE428 or XYZ.”

The still image encoder 104 performs, for example, JPEG encoding on theinput image data to obtain encoded video data. The still image encoder104 receives input of dynamic range information and color gamutinformation of the image data. The still image encoder 104 inserts thedynamic range information and color gamut information into the encodeddata. Here, the dynamic range information is information indicating anelectro-optical transfer characteristic (a transfer function)corresponding to an opto-electrical transfer characteristic that theimage data has.

For the information indicating the electro-optical transfercharacteristic (the transfer function), the still image encoder 104uses, for example, a value of a gamma tag stipulated in an Exchangeableimage file format (Exit) standard defined in the JPEG standard.Currently, “16 (gamma=BT.709-5 transfer function (SDR))” is defined;however, for other values, “10-bit BT.2020 transfer function (SDR),”“SMPTE 2084 transfer function (HDR1),” “HDR (HDR2),” and the like aredefined and used.

In addition, for the color gamut information, the still image encoder104 uses, for example, a value of a color space tag stipulated in theExif standard defined in the JPEG standard. Currently, “1(sRGB=BT.709-5)” is defined; however, for other values, “BT.2020,”“SMPTE 428 or XYZ,” and the like are defined and used.

The data service encoder 103 performs an encoding process on the inputgraphics data and further on the encoded data input from the still imageencoder 104, and thereby generates a data service stream DS as acomponent stream. The data service stream DS includes image data andgraphics data as component data.

The data service encoder 103 receives input of dynamic range informationand color gamut information of the graphics data. The data serviceencoder 103 inserts the dynamic range information and color gamutinformation into the data service stream DS. Here, the dynamic rangeinformation is the information indicating an electro-optical transfercharacteristic (the transfer function) corresponding to anopto-electrical transfer characteristic that the graphics data has.

For the information indicating the electro-optical transfercharacteristic (the transfer function), the data service encoder 103,for example, defines expanded dynamic range information “D_range” asrepresenting “BT.709-5 transfer function (SDR),” “10-bit BT.2020transfer function (SDR),” “SMPTE 2084 transfer function (HDR1),” “HDR(HDR2),” or the like. In addition, for the color gamut information, thedata service encoder 103 uses, for example, the item of“gfx.color_management.mode” to indicate a color gamut of “BT.709-5,”“BT.2020,” “SMPTE 428 or XYZ,” or the like.

The subtitle encoder 105 performs an encoding process on the inputsubtitle data, and thereby generates a subtitle stream SS as a componentstream. The subtitle stream SS includes subtitle data as component data.Although detailed description thereof is omitted, the subtitle stream SSincludes text information of subtitles such as Timed Text MarkupLanguage (TTML), or bitmap data of subtitles.

The subtitle encoder 105 receives input of dynamic range information andcolor gamut information of the subtitle data. The subtitle encoder 105inserts the dynamic range information and color gamut information intothe subtitle stream SS.

When the subtitle stream SS includes the TTML as text information ofsubtitles, the subtitle encoder 105 inserts the color gamut informationand dynamic range information of the subtitle data using, for example,an element of metadata present in a header of a TTML structure, insertsthe color gamut information and dynamic range information of thesubtitle data using an element of styling extension present in theheader of the TTML structure, or inserts a segment including the colorgamut information and dynamic range information of the subtitle datainto the subtitle stream SS.

On the other hand, when the subtitle stream SS includes the bitmap dataof subtitles, the subtitle encoder 105 inserts a segment including thecolor gamut information and dynamic range information of the subtitledata into the subtitle stream SS.

In this case, the information indicating the electro-optical transfercharacteristic (the transfer function) indicates an electro-opticaltransfer characteristic of, for example, “BT.709-5 transfer function(HDR1),” “10-bit BT.2020 transfer function (SDR),” “SMPTE 2084 transferfunction (HDR1),” or “HDR (HDR2).” Note that “HDR (HDR2)” is for aso-called hybrid gamma, not a PQ curve. In addition, the color gamutinformation indicates a color gamut of “BT.709-5,” “BT.2020,” or “SMPTE428 or XYZ.”

The container encoder 106 generates a transport stream (an MPEG-2transport stream or a transport stream of MMT) including the videostream VS generated by the video encoder 102, the data service stream DSgenerated by the data service encoder 103, and the subtitle stream SSgenerated by the subtitle encoder 105. The transmission unit 107 putsthe transport stream in a broadcasting wave or packets of a network tobe transmitted to the service reception device 200.

At that time, the container encoder 106 inserts identificationinformation indicating the type of transmission video data that thevideo stream VS included in the transport stream has into the transportstream so that the identification information indicates the type of thetransmission video data after switching from the timing a predeterminedamount of time or more earlier than the switching timing of the type ofthe transmission video data. By managing the insertion of theidentification information in this way, the reception side is notifiedof dynamic switching of the transmission video data.

FIG. 4 shows relations between timings Sn (S0, S1, S2, . . . ) at whichSDR transmission video data (an SDR service) and HDR transmission videodata (an HDR service) are switched and insertion timings Tn (T0, T1, T2,. . . ) of identification information for identifying transmission videodata after the switching. To satisfy the following expression (1), atiming Tn is set as a timing t (a predetermined amount of time) or moreearlier than a timing Sn. Note that the illustrated example shows a casein which Sn−Tn=t (here, t is a positive value).

Sn−Tn>=t  (1)

The container encoder 106 inserts, for example, a newly defined HDRvideo descriptor (HDR_video_descriptor) to correspond to the videostream VS. When the transport stream is an MPEG-2 transport stream, forexample, the descriptor is inserted to be subordinate to a program maptable (PMT) or an event information table (EIT). In addition, when thetransport stream is a transport stream of MMT, the descriptor isinserted to be subordinate to an MMT package table (MP table or MPT), oran event information table (EIT).

FIG. 5 shows an example of a structure (a syntax) of the HDR videodescriptor, and FIG. 6 shows content (semantics) of principalinformation in the structure example. The 8-bit field “descriptor_tag”indicates the type of the descriptor and indicates an HDR videodescriptor here. The 8-bit field “descriptor_length” indicates a length(a size) of the descriptor and indicates the number of succeeding bytesas the length of the descriptor.

The 1-bit flag information “HDR_SDR_flag” indicates whether a targetstream is an HDR stream or an SDR stream. “1” indicates an HDR stream,and “0” indicates an SDR stream. The 1-bit flag information of“video_characteristics_info_flag” indicates whether characteristicinformation exists. “1” indicates that characteristic informationexists, and “0” indicates that no characteristic information exists.

When the “video_characteristics_info_flag” is “1,” 8-bit fields“transferfunction,” “color_space,” and “referencelevel” exist. The 8-bitfield “transferfunction” indicates an electro-optical transfercharacteristic (an EOTF characteristic). In other words, this fieldindicates an electro-optical transfer characteristic corresponding to anopto-electrical transfer characteristic that the transmission video datahas. For example, “1” indicates “BT.709-5 transfer function (SDR),” “14”indicates “10-bit BT.2020 transfer function (SDR),” “16” indicates“SMPTE 2084 transfer function (HDR1),” and “25” indicates “HDR (HDR2).”Note that, although “HDR (HDR2)” indicates an HDR electro-opticaltransfer characteristic, it is considered to be partially compatiblewith a gamma characteristic and luminance and transmissioncharacteristics of the past, rather than with a PQ curve, or to havecharacteristics close thereto.

The 8-bit field “color_space” indicates a color space. For example, “1”indicates “BT.709-5,” “9” indicates “BT.2020,” and “10” indicates “SMPTE428 or XYZ.”

The 8-bit field “referencelevel” indicates a reference level. In thiscase, a value in a relative range in which values are normalized to “1”at the maximum that is designated to be a value from 0 to 100 isdescribed as the reference level. The reception side recognizes a resultobtained by dividing this value by 100 as a normalized relativereference level. The 8-bit field “content_peak_luminance” indicates arelative luminance value (expressed in %) corresponding to the peakvalue of transmission codes included in an image. The relative valuehelps, for example, in control of a knee curve which will be describedbelow.

In addition, the container encoder 106 inserts the type of subtitle datathat the subtitle stream SS included in the transport stream has, i.e.,identification information indicating whether the data is SDR data orHDR data, into the transport stream so that the identificationinformation indicate the type of subtitle data after switching from thetiming a predetermined amount of time or more earlier than a switchingtiming of the type of the subtitle data. By managing the insertion ofthe identification information in this way, the reception side isnotified of dynamic switching of the subtitle data.

The container encoder 106 inserts, for example, a newly defined HDRsubtitle descriptor (HDR_subtitle_descriptor) to correspond to thesubtitle stream SS. When the transport stream is an MPEG-2 transportstream, for example, this descriptor is inserted to be subordinate to aprogram map table (PMT). In addition, when the transport stream is atransport stream of MMT, this descriptor is inserted to be subordinateto an MMT package table (MP table or MPT).

FIG. 7 shows an example of a structure (a syntax) of an HDR subtitledescriptor. The 8-bit field “descriptor_tag” indicates the type of thedescriptor and indicates the HDR subtitle descriptor here. The 8-bitfield “descriptor_length” indicates the length (the size) of thedescriptor and indicates the number of succeeding bytes as the length ofthe descriptor.

The 1-bit flag information “HDR_SDR_flag” indicates whether a targetstream is an HDR stream or an SDR stream. “1” indicates an HDR stream,and “0” indicates an SDR stream. The 1-bit flag field“subtitle_display_characteristics_info_flag” indicates whethercharacteristic information exists. “1” indicates that characteristicinformation exists, and “0” indicates that no characteristic informationexists. When “subtitle_display_characteristics_info_flag” is 1, the8-bit fields “transferfunction,” “color_space,” and “referencelevel”exist.

The 8-bit field “transferfunction” indicates an electro-optical transfercharacteristic (an EOTF characteristic). In other words, this fieldindicates an electro-optical transfer characteristic corresponding to anopto-electrical transfer characteristic that the transmission video datahas. For example, “1” indicates “BT.709-5 transfer function (SDR),” “14”indicates “10-bit BT.2020 transfer function (SDR),” “16” indicates“SMPTE 2084 transfer function (HDR1),” and “25” indicates “HDR (HDR2).”Note that, although “HDR (HDR2)” indicates an HDR electro-opticaltransfer characteristic, it is considered to be partially compatiblewith a gamma characteristic and luminance and transmissioncharacteristics of the past, rather than with a PQ curve, or to havecharacteristics close thereto.

The 8-bit field “color_space” indicates a color space. For example, “1”indicates “BT.709-5,” “9” indicates “BT.2020,” and “10” indicates “SMPTE428 or XYZ.” The 8-bit field “referencelevel” indicates a referencelevel. In this case, a value in a relative range in which values arenormalized to “1” at the maximum that is designated to be a value from 0to 100 is described as the reference level. The reception siderecognizes the result obtained by dividing this value by 100 as thenormalized relative reference level.

FIG. 8 shows an example of a structure of a MPEG-2 transport stream. Inthis example of the structure, not only do a PES packet of the videostream VS identified as PID1 “Video PES” and a PES packet of thesubtitle stream SS identified as PID2 “Subtitle PES” exist, but the dataservice stream DS transmitted in a carousel scheme also exists. Notethat, although the subtitle stream SS is transmitted as a PES asdescribed above and in the carousel scheme like the data service stream,the substance of the subtitle stream SS does not change accordingly.

In addition, a transport stream TS includes a program map table (PMT) asprogram specific information (PSI). The PSI is information describing aprogram to which each elementary stream included in the transport streambelongs. The PMT includes a program loop describing information for theentire program.

The PMT has elementary stream loops having information for eachelementary stream in. In this structure example, a video elementarystream loop (a video ES loop) corresponding to the video stream VS and asubtitle elementary stream loop (a subtitle ES loop) corresponding tothe subtitle stream SS exist.

Information such as a stream type and a packet identifier (PID) of thevideo stream VS as well as a descriptor describing information withregard to the video stream VS is disposed in the video elementary streamloop. As one type of the descriptor, the above-described HDR videodescriptor (see FIG. 5) is disposed. Note that a structure in which theHDR video descriptor is disposed to be subordinate to an eventinformation table (EIT) as illustrated by the dashed line is alsoconsidered.

In addition, information such as a stream type and a packet identifier(PID) of the subtitle stream SS as well as a descriptor describinginformation with regard to the subtitle stream SS is disposed in thesubtitle elementary stream loop. As one type of the descriptor, theabove-described HDR subtitle descriptor (see FIG. 7) is disposed.

FIG. 9 shows an example of a structure of a transport stream of MMT.When the packet type is “MPU,” an MPU packet of the video stream VSidentified as ID1 “MPU video” and an MPU packet of the subtitle streamSS identified as ID2 “MPU subtitle” are disposed in the transport streamof MMT. In addition, when the packet type is “non-timed packet,” thedata service stream DS is disposed in the transport stream of MMT.

In addition, when the packet type is “message,” various message packetsare disposed in the transport stream of MMT. There is a packet access(PA) message packet as one of such message packets. The PA messagepacket includes a table such as an MPT.

Information such as an asset type (Asset_type) and a packet ID(Packet_id) of the video stream VS serving as an asset as well as adescriptor describing information with regard to the video stream VS isdisposed in the MPT. As one type of the descriptor, the above-describedHDR video descriptor (see FIG. 5) is disposed. Note that the structurein which the HDR video descriptor is disposed to be subordinate to anevent information table (EIT) as illustrated by the dashed line is alsoconsidered.

Furthermore, information such as an asset type (Asset_type) and a packetID (Packet_id) of the subtitle stream SS serving as an asset as well asa descriptor describing information with regard to the subtitle streamSS is disposed in the MPT. As one type of the descriptor, theabove-described HDR subtitle descriptor (see FIG. 7) is disposed.

An operation of the service transmission system 100 shown in FIG. 2 willbe briefly described. Transmission video data as well as dynamic rangeinformation and color gamut information of the transmission video datais input to the video encoder 102. Here, the dynamic range informationis information indicating an electro-optical transfer characteristic (atransfer function) corresponding to an opto-electrical transfercharacteristic that the transmission video data has.

The transmission video data input as described above is obtained byswitching between a plurality of types of transmission video data. Theplurality of types of transmission video data include, for example, SDRtransmission video data obtained by applying an SDR opto-electricaltransfer to SDR video data, and HDR transmission video data obtained byapplying an HDR opto-electrical transfer to HDR video data.

The video encoder 102 performs encoding, for example, MPEG4-AVC or HEVCon the transmission video data to obtain encoded video data, andgenerates a video stream VS as a component stream including the encodedvideo data. The video stream VS includes the transmission video data ascomponent data.

In addition, upon generating the video stream VS as described above, thevideo encoder 102 inserts the dynamic range information and the colorgamut information into the video stream VS. In this case, metainformation such as information indicating the electro-optical transfercharacteristic (the transfer function) corresponding to theopto-electrical transfer characteristic that the transmission video datahas, the color gamut information of the transmission video data, andinformation indicating a reference level is inserted into a videousability information (VUI) region of an SPS NAL unit of an access unit(AU). In addition, an SEI message having the meta information such asthe information indicating the electro-optical transfer characteristic(the transfer function) corresponding to the opto-electrical transfercharacteristic that the transmission video data has, and the informationof the reference level is inserted into the “SEI” part of the accessunit (AU).

Further, image data as well as dynamic range information and color gamutinformation of the image data is input to the still image encoder 104.Here, the dynamic range information is the information indicating theelectro-optical transfer characteristic (the transfer function)corresponding to the opto-electrical transfer characteristic that thetransmission video data has.

The still image encoder 104 performs, for example, JPEG encoding on theimage data to obtain encoded video data. At this time, the dynamic rangeinformation and the color gamut information are inserted into theencoded data. In this case, for the information indicating theelectro-optical transfer characteristic (the transfer function), forexample, a value of a gamma tag stipulated in the Exchangeable imagefile format (Exif) standard defined in the JPEG standard is used to beinserted. In addition, for the color gamut information, for example, avalue of a color space tag stipulated in the Exif standard defined inthe JPEG standard is used to be inserted.

Further, graphics data as well as dynamic range information and colorgamut information of the graphics data are input to the data serviceencoder 103. Here, the dynamic range information is the informationindicating the electro-optical transfer characteristic (the transferfunction) corresponding to the opto-electrical transfer characteristicthat the transmission video data has. The encoded data obtained by thestill image encoder 104 is further input to the data service encoder103.

The data service encoder 103 performs an encoding process on thegraphics data and further on the encoded data input from the still imageencoder 104, and thereby generates a data service stream DS as acomponent stream. The data service stream DS includes the image data andthe graphics data as component data.

Furthermore, upon generating the data service stream DS as descriedabove, the data service encoder 103 inserts the dynamic rangeinformation and the color gamut information into the data service streamDS. In this case, for the information indicating the electro-opticaltransfer characteristic (the transfer function), for example, dynamicrange information “D_range” is expanded, defined, and insertedthereinto. In addition, for the color gamut information, for example,the item of “gfx.color_management.mode” is used to be insertedthereinto.

In addition, the subtitle encoder 105 receives subtitle data as well asdynamic range information and color gamut information of the subtitledata. Here, the dynamic range information is the information indicatingthe electro-optical transfer characteristic (the transfer function)corresponding to the opto-electrical transfer characteristic that thetransmission video data has.

The subtitle encoder 105 performs an encoding process on the subtitledata, and thereby generates a subtitle stream SS as a component stream.The subtitle stream SS includes the subtitle data (subtitle textinformation such as TTML or subtitle bitmap data) as component data.

Furthermore, upon generating the subtitle stream SS as described above,the subtitle encoder 105 inserts the dynamic range information and thecolor gamut information into the subtitle stream SS.

Here, when the subtitle stream SS includes TTML as subtitle textinformation, the color gamut information and the dynamic rangeinformation of the subtitle data are inserted using, for example, anelement of metadata present in a header of a TTML structure. Inaddition, when the subtitle stream SS includes the subtitle bitmap data,a segment including the color gamut information and the dynamic rangeinformation of the subtitle data, for example, is inserted into thesubtitle stream SS.

The video stream VS generated by the video encoder 102, the data servicestream DS generated by the data service encoder 103, and the subtitlestream SS generated by the subtitle encoder 105 are supplied to thecontainer encoder 106. The container encoder 106 generates a transportstream (an MPEG-2 transport stream or a transport stream of MMT)including these streams.

In addition, upon generating the transport stream as described above,the container encoder 106 inserts identification information indicatingthe type of the transmission video data that the video stream VSincluded in this transport stream has into the transport stream so thatthe identification information indicates the type of the transmissionvideo data after switching from a timing the predetermined amount oftime or more earlier than a switching timing of the video stream VS.Specifically, the HDR video descriptor (see FIG. 5) is inserted tocorrespond to the video stream VS. In addition, the container encoder106 further inserts the HDR subtitle descriptor (see FIG. 7) into thetransport stream to correspond to the subtitle stream SS.

The transport stream generated by the container encoder 106 is suppliedto the transmission unit 107. The transmission unit 107 puts thetransport stream in a broadcasting wave or packets of a network totransmit the transport stream to the service reception device 200.

Configuration Example of Service Reception Device

FIG. 10 shows an example of a structure of the service reception device200. This service reception device 200 has a control unit 201, areception unit 202, a container decoder 203, a video decoder 204, a dataservice decoder 205, a still image decoder 206, a subtitle decoder 207,an OSD (On-screen display) unit 208, a screen composition processingunit 209, and a monitor 210.

The control unit 201 is configured to include a central processing unit(CPU) to control operations of the units of the service reception device200 using a control program. The reception unit 202 receives a transportstream (an MPEG-2 transport stream or a transport stream of MMT) servingas a container put in a broadcasting wave or packets of a network andtransmitted by the service transmission system 100 (see FIG. 2). Thecontainer decoder 203 extracts a video stream VS, a data service streamDS, and a subtitle stream SS from the transport stream.

In addition, the container decoder 203 extracts various kinds ofinformation inserted into the transport stream and transmits theinformation to the control unit 201. This information includes theabove-described HDR video descriptor (see FIG. 5) and HDR subtitledescriptor (see FIG. 7) describing identification information oftransmission video data.

The control unit 201 recognizes whether the transmission video dataincluded in the video stream VS is SDR transmission video data or HDRtransmission video data based on a description of the HDR videodescriptor. As described above, the identification information foridentifying the type of the transmission video data has been insertedinto the transport stream so that the identification informationindicates the type of the transmission video data after switching from atiming the predetermined amount of time or more earlier than theswitching timing of the type of the transmission video data.

In addition, the control unit 201 recognizes the type of subtitle datathat the subtitle stream SS has, i.e., whether the subtitle data is SDRdata or HDR data, based on the description of the HDR subtitledescriptor. Identification information indicating the type of thesubtitle data is inserted into the transport stream so that theidentification information indicates a type of the transmission videodata after switching from a timing the predetermined amount of time ormore earlier than the switching timing of the type of the subtitle data,as described above.

The video decoder 204 performs a decoding process on the video stream VSextracted by the container decoder 203 to obtain the transmission videodata as well as dynamic range information and color gamut information ofthe transmission video data. Here, the dynamic range information isinformation indicating an electro-optical transfer characteristic (atransfer function) corresponding to an opto-electrical transfercharacteristic that the transmission video data has.

The data service decoder 205 performs a decoding process on the dataservice stream DS extracted by the container decoder 203 to obtaingraphics data (bitmap data), dynamic range information and color gamutinformation of the graphics data and encoded data of image data. Thestill image decoder 206 performs a decoding process on the encoded dataobtained by the data service decoder 205 to obtain the image data aswell as dynamic range information and color gamut information of theimage data.

The subtitle decoder 207 performs a decoding process on the subtitlestream SS extracted by the container decoder 203 to obtain subtitle data(bitmap data) as well as dynamic range information and color gamutinformation of the subtitle data. The OSD unit 208 outputs graphics data(bitmap data) for OSD (On-screen display) as well as the dynamic rangeinformation and color gamut information of the graphics data.

The screen composition processing unit 209 performs compositing on thetransmission video data obtained by the video decoder 204, the graphicsdata obtained by the data service decoder 205, the image data obtainedby the still image decoder 206, the subtitle data obtained by thesubtitle decoder 207, and the graphics data obtained by the OSD unit208, and thereby generates display image data corresponding to displayperformance of the monitor 210. The monitor 210 displays an image basedon the display image data, having display performance such as HDR and awide color gamut or SDR and a standard color gamut.

The screen composition processing unit 209 performs a luminance mappingprocess on each piece of the data based on the dynamic range informationof the data to match the display performance and performs compositingthereon. In addition, the screen composition processing unit 209performs a color gamut conversion process on each piece of the databased on the color gamut information of the data to match the displayperformance and performs compositing thereon.

FIG. 11 shows an overview of the luminance mapping process when thedisplay performance is HDR. The luminance mapping process is performedon the transmission video data and the image data such that, when thedynamic range information indicates HDR, a maximum value of a data bitexpression range corresponds to a maximum brightness level, and when thedynamic range information indicates SDR, the maximum value of the databit expression range corresponds to a reference brightness level.

In addition, the luminance mapping process is performed on the graphicsdata and the subtitle data such that, when the dynamic range informationindicates HDR, i.e., when the data has bright components, the maximumvalue of the data bit expression range corresponds to the maximumbrightness level, and when the dynamic range information indicates SDR,i.e., when the data has no bright components, the maximum value of thedata bit expression range corresponds to the reference brightness level.

As reference brightness level of this case, a reference brightness level(referencelevel; see FIG. 5) set to correspond to the transmission videodata and the image data, for example, can be used, and a referencebrightness level (referencelevel; see FIG. 7) set to correspond to thegraphics data and the subtitle data, for example, can be used.Furthermore, in this case, the reference brightness level(referencelevel) set to correspond to the transmission video data andthe image data can be used for the transmission video data and the imagedata, and the reference brightness level (referencelevel) set tocorrespond to the graphics data and the subtitle data can be used forthe graphics data and the subtitle data. In addition, although thereference brightness level may be 100 nits (100% luminance), brightnessthereof is not limited. The reference brightness level may be set inadvance to, for example, 200 nits (200% luminance), 300 nits (300%luminance), or the like.

FIG. 12 shows an example of a structure of the screen compositionprocessing unit 209 when display performance is HDR and has wide colorgamut. This screen composition processing unit 209 has color gamutconversion units 211 a, 211 b, 211 c, and 211 d, luminance mapping units212 a, 212 b, 212 c, and 212 d, a compositing unit 213, and an HDRelectro-optical transfer unit 214.

The transmission video data supplied from the video decoder 204 issupplied to a series circuit of the color gamut conversion unit 211 aand the luminance mapping unit 212 a. The color gamut conversion unit211 a converts the color gamut of the transmission video data into awide color gamut to match the display performance of a display based onthe color gamut information. For example, when the color gamut of thetransmission video data is “BT.709-5 =sRGB” and the color gamut thatmatches the display performance is “BT.2020 =ITUR2020,” the color gamutof the transmission video data is converted from “BT.709-5” to“BT.2020.” Note that, when the color gamut of the transmission videodata is the same as the wide color gamut that matches the displayperformance, the color gamut conversion unit 211 a does nothingsubstantial, and outputs the input data as it is.

The luminance mapping unit 212 a performs luminance mapping to cause thetransmission video data to match a HDR display performance based on itsdynamic range information. The luminance mapping unit 212 a isconstituted by a series circuit of an electro-optical transfer unit (anEOTF unit) 221 and an opto-electrical transfer unit (an OETF unit) 222as shown in FIG. 13.

The electro-optical transfer unit (the EOFT unit) 221 performs atransfer on the input transmission video data to change anopto-electrical transfer characteristic (an OETF characteristic) appliedto this transmission video data into a linear optical spacecharacteristic. The opto-electrical transfer unit (the OETF unit) 222performs an opto-electrical transfer on the output data of theelectro-optical transfer unit 221 based on the opposite opto-electricaltransfer characteristic (the OETF characteristic) to the electro-opticaltransfer characteristic (the EOTF characteristic) of the HDRelectro-optical transfer unit 214.

Here, a case in which the input transmission video data is SDRtransmission video data will be described. In this case, the luminancemapping unit 212 a performs the luminance mapping process to convert theSDR transmission video data into HDR transmission video data. In thiscase, the luminance mapping unit 212 a, which is configured as a seriescircuit of an SDR electro-optical transfer unit 231 and an HDRopto-electrical transfer unit 232 as shown in FIG. 14(a), performs aconversion from an SDR bit space into an HDR bit space based on thereference brightness level.

The SDR electro-optical transfer unit 231 performs an electro-opticaltransfer on the SDR transmission video data based on an SDRelectro-optical transfer characteristic indicated by arrow a in FIG.14(b). In this case, luminance levels 0 to 100% of the input SDRtransmission video data hit 100 nits (=100 cd/m²) at maximum in a linearoptical space. Here, “100 nits” indicates brightness of the referencelevel. Note that the brightness of the reference level is not limited to100 nits, and may be, for example, 200 nits or 300 nits. This alsoapplies to the following other examples.

In addition, the HDR opto-electrical transfer unit 232 performs anopto-electrical transfer based on an HDR opto-electrical transfercharacteristic indicated by arrow b in FIG. 14(c). In this case, outputdata of the SDR electro-optical transfer unit 231 is re-assigned to 0 to100% in the transmission range of 0 to N*100%. Accordingly, the SDRtransmission video data, which has been expressed in a fully encodedbit, is concentrated on a part of the transmission range after beingre-assigned as HDR transmission video data.

Next, a case in which the input transmission video data is HDRtransmission video data and an opto-electrical transfer characteristic(an OETF characteristic) that the HDR transmission video data has doesnot coincide with the opposite characteristic of the electro-opticaltransfer characteristic (the EOTF characteristic) in the HDRelectro-optical transfer unit 214 will be described. Note that, when theopto-electrical transfer characteristic that the HDR transmission videodata has coincides with the opposite characteristic of theelectro-optical transfer characteristic in the HDR electro-opticaltransfer unit 214, the luminance mapping unit 212 a does nothingsubstantial, and outputs the input data as it is.

In this case, the luminance mapping unit 212 a performs the luminancemapping process to convert the data from HDR1 transmission video datainto HDR2 transmission video data. In this case, the luminance mappingunit 212 a is configured as a series circuit of an HDR1 electro-opticaltransfer unit 241 and an HDR2 opto-electrical transfer unit 242 as shownin FIG. 15(a).

The HDR1 electro-optical transfer unit 241 performs an electro-opticaltransfer on the HDR1 transmission video data based on an HDR1electro-optical transfer characteristic indicated by arrow a in FIG.15(b). In this case, luminance levels in the transmission range of 0 toN*100% of the input HDR1 transmission video data correspond to N*100nits (=K1) at maximum in a linear optical space.

In addition, when N*100% of HDR1 is greater than M*100% of HDR2 in thiscase as illustrated, the HDR1 electro-optical transfer unit 241 performsa luminance conversion on electro-optical transfer input signals so thatthe signal in the luminance levels in the range of 100 to N*100% hasluminance levels in the range of 100 to M*100% as indicated by a kneecurve (indicated by arrow b in FIG. 15(b)). Note that, in FIG. 15(b),“K1” indicates the luminance value [nits] corresponding to N*100%, and“K2 indicates the luminance value [nits] corresponding to M*100%. Notethat, although it is not illustrated, no such luminance conversion isperformed when N*100% of HDR1 is equal to or lower than M*100% of HDR2.

In addition, the HDR2 opto-electrical transfer unit 242 performs anopto-electrical transfer based on an HDR2 opto-electrical transfercharacteristic indicated by arrow c of FIG. 15(c). In this case, outputdata of the HDR1 electro-optical transfer unit 241 is re-assigned in theentire transmission range of 0 to M*100%.

Returning to FIG. 12, the image data supplied from the still imagedecoder 206 is supplied to a series circuit of the color gamutconversion unit 211 b and the luminance mapping unit 212 b. The colorgamut conversion unit 211 b converts the color gamut of the image datainto a wide color gamut based on its color gamut information to matchthe display performance. The luminance mapping unit 212 b performsluminance matching on this image data to match the HDR displayperformance based on its dynamic range information. Note that, sincedetails of the color gamut conversion unit 211 b and the luminancemapping unit 212 b are similar to those of the color gamut conversionunit 211 a and the luminance mapping unit 212 a corresponding to theabove-described transmission video data, they are omitted.

In addition, the subtitle data supplied from the subtitle decoder 207 issupplied to a series circuit of the color gamut conversion unit 211 cand the luminance mapping unit 212 c. The color gamut conversion unit211 c converts the color gamut of the subtitle data into a wide colorgamut based on its color gamut information to match the displayperformance. The luminance mapping unit 212 c performs luminance mappingon the subtitle data based on its dynamic range information to match theHDR display performance. Note that, since details of the color gamutconversion unit 211 c and the luminance mapping unit 212 c are similarto those of the color gamut conversion unit 211 a and the luminancemapping unit 212 a corresponding to the above-described transmissionvideo data, they are omitted.

Furthermore, the graphics data supplied from the data service decoder205 or the OSD unit 208 is supplied to a series circuit of the colorgamut conversion unit 211 d and the luminance mapping unit 212 d. Thecolor gamut conversion unit 211 d converts the color gamut of thegraphics data into a wide color gamut based on its color gamutinformation to match the display performance. The luminance mapping unit212 d performs luminance mapping on the graphics data based on itsdynamic range information to match the HDR display performance. Notethat, since details of the color gamut conversion unit 211 d and theluminance mapping unit 212 d are similar to those of the color gamutconversion unit 211 a and the luminance mapping unit 212 a correspondingto the above-described transmission video data, they are omitted.

The transmission video data, the image data, the subtitle data, and thegraphics data that have undergone the processes of color gamutconversion and luminance mapping are supplied to the compositing unit213. Although detailed description of the compositing unit 213 isomitted, the compositing unit performs compositing on the data based onscreen configuration information. Output data of the compositing unit213 is supplied to the HDR electro-optical transfer unit 214. The HDRelectro-optical transfer unit 214 performs an electro-optical transferon the output data of the compositing unit 213 based on the HDRelectro-optical transfer characteristic, and thereby obtains displayimage data appropriate for the HDR display performance with a wide colorgamut.

Note that an example in which the monitor 210 has the HDR displayperformance with a wide color gamut and the screen compositionprocessing unit 209 obtains display image data appropriate for the HDRdisplay performance with a wide color gamut has been described. When themonitor 210 has SDR display performance with a normal color gamut suchas sRGB, the screen composition processing unit 209 is configured toobtain display image data appropriate for the SDR display performancewith a normal color gamut.

In this case, each of the color gamut conversion units of the screencomposition processing unit 209 shown in FIG. 12 converts the colorgamut of each piece of data into the normal color gamut that matches thedisplay performance based on the color gamut information. In addition,each of the luminance mapping units of the screen composition processingunit 209 shown in FIG. 12 performs luminance matching on each piece ofthe data to match the SDR display performance based on the dynamic rangeinformation. Note that the HDR electro-optical transfer unit 214 servesas an SDR electro-optical transfer unit in the screen compositionprocessing unit 209 shown in FIG. 12.

Here, a case in which the input transmission video data is HDRtransmission video data will be described. In this case, the luminancemapping units perform the luminance mapping process, and thereby convertthe HDR transmission video data into SDR transmission video data. Inthis case, each luminance mapping units is constituted by a seriescircuit of an HDR electro-optical transfer unit 251 and an SDRopto-electrical transfer unit 252 as shown in FIG. 16(a).

The HDR electro-optical transfer unit 251 performs an electro-opticaltransfer on the HDR transmission video data based on the HDRelectro-optical transfer characteristic indicated by arrow a in FIG.16(b). In this case, the luminance levels in the transmission range of 0to N*100% of the input HDR transmission video data hit N*100 nits (=100cd/m²) at maximum in a linear optical space.

In addition, in this case, the HDR electro-optical transfer unit 251further performs a luminance conversion on an electro-optical transferinput signal so that the signal in the range from a luminance level atP%, which is lower than 100%, to the luminance level at N*100% hasluminance levels in the transmission range equal to or lower than 100%in the SDR OETF as indicated by a knee curve (indicated by arrow b ofFIG. 16(b)).

Furthermore, the SDR opto-electrical transfer unit 252 performs anopto-electrical transfer based on an SDR opto-electrical transfercharacteristic indicated by arrow c in FIG. 16(c). In this case, theoutput data of the HDR electro-optical transfer unit 251 is re-assignedin the entire transmission range of 0 to 100%.

An operation of the service reception device 200 shown in FIG. 10 willbe briefly described. The reception unit 202 receives a transport stream(an MPEG-2 transport stream or a transport stream of MMT) put in abroadcasting wave or packets of a network and transmitted from theservice transmission system 100. The transport stream is supplied to thecontainer decoder 203. The container decoder 203 extracts a video streamVS, a data service stream DS, and a subtitle stream SS from thetransport stream.

In addition, the container decoder 203 extracts various kinds ofinformation inserted into the transport stream serving as a container,and transmits the information to the control unit 201. This informationalso includes the HDR video descriptor (see FIG. 5) and HDR subtitledescriptor (see FIG. 7) described above.

The control unit 201 recognizes whether transmission video data includedin the video stream VS is SDR transmission video data or HDRtransmission video data based on description of the HDR videodescriptor. In addition, the control unit 201 recognizes the type ofsubtitle data that the subtitle stream SS has, i.e., whether its type isSDR data or HDR data, based on the description of the HDR subtitledescriptor.

The video stream VS extracted by the container decoder 203 is suppliedto the video decoder 204. The video decoder 204 performs a decodingprocess on the video stream VS, and thereby obtains the transmissionvideo data as well as dynamic range information and color gamutinformation of the transmission video data.

In addition, the data service stream DS extracted by the containerdecoder 203 is supplied to the data service decoder 205. The dataservice decoder 205 performs a decoding process on the data servicestream DS, and thereby obtains graphics data (bitmap data) as well asdynamic range information and color gamut information of the graphicsdata, and also obtains encoded data of image data.

The encoded data of the image data obtained by the data service decoder205 is supplied to the still image decoder 206. The still image decoder206 performs a decoding process on the encoded data, and thereby obtainsthe image data as well as dynamic range information and color gamutinformation of the image data.

Furthermore, the subtitle stream SS extracted by the container decoder203 is supplied to the subtitle decoder 207. The subtitle decoder 207performs a decoding process on the subtitle stream SS, and therebyobtains subtitle data (bitmap data) as well as dynamic range informationand color gamut information of the subtitle data.

The transmission video data obtained by the video decoder 204, thegraphics data obtained by the data service decoder 205, the image dataobtained by the still image decoder 206, the subtitle data obtained bythe subtitle decoder 207, and the graphics data obtained by the OSD unit208 are supplied to the screen composition processing unit 209 alongwith their dynamic range information and color gamut information.

The screen composition processing unit 209 performs compositing on thedata, and thereby generates display image data appropriate for thedisplay performance of the monitor 210. In this case, each piece of thedata undergoes a color gamut conversion process based on the color gamutinformation of the data to match the display performance, furtherundergoes a luminance mapping process based on the dynamic rangeinformation of the data to match the display performance, and thenundergoes compositing. The display image data generated by the screencomposition processing unit 209 is supplied to the monitor 210, and themonitor 210 displays an image based on the display image data.

As described above, in the transmission and reception system 10 shown inFIG. 1, the service transmission system 100 inserts dynamic rangeinformation of component data (transmission video data, image data,graphics data, and subtitle data) that each component stream has intoeach of the component streams (a video stream VS, a data service streamDS, and a subtitle stream SS). Thus, a reception side can perform aluminance mapping process on each piece of the component data based onits dynamic range information to match display performance and performcompositing thereon to obtain output data.

In this case, since the characteristic of the electro-optical transferperformed on this output data can be fixed (see the HDR electro-opticaltransfer unit 214 of FIG. 12), occurrence of an image disturbance causedby switching of the electro-optical transfer characteristic can beprevented. For example, when an image based on video data is displayedalong with graphics display, even if the image based on the video datais switched from SDR to HDR or from HDR to SDR, the graphics displayshows no change in color or brightness. In addition, in that case, aluminance mapping process is performed on each piece of component datato match display performance, and therefore display based on thecomponent data can be performed in a proper luminance state at alltimes.

For example, FIG. 17(a) and (b) show examples of graphics displaythrough an operation of a so-called “d button” that is provided as oneof broadcasting services. A dynamic image based on transmission videodata is displayed in a small window on an upper right side, and a stillimage based on image data is displayed on a lower left side.

FIG. 17(a) is of an example of a case in which characteristics of anelectro-optical transfer performed on the transmission video data areswitched according to whether the transmission video data is SDRtransmission video data or HDR transmission video data. In this case,color and luminance of the graphics display are affected when switchingbetween an SDR image display time and an HDR image display time isperformed.

FIG. 17(b) is an example of a case in which characteristics of anelectro-optical transfer performed on the transmission video data arefixed regardless of whether the transmission video data is SDRtransmission video data or HDR transmission video data as in anembodiment of the present technology. In this case, color and luminanceof the graphics display are not affected when switching between an SDRimage display time and an HDR image display time is performed.

In addition, in the transmission and reception system 10 shown in FIG.1, the service transmission system 100 inserts color gamut informationof component data that each of component streams has into the componentstreams. Thus, the reception side can obtain output data by performing acolor gamut conversion on the component data based on its color gamutinformation to match display performance and compositing thereon, andtherefore display based on the component data can be performed in aproper color state at all times.

2. Modified Example

Note that, although the transmission and reception system 10 constitutedby the service transmission system 100 and the service reception device200 has been introduced in the above-described embodiment, aconfiguration of the transmission and reception system to which thepresent technology can be applied is not limited thereto. For example,the service reception device 200 may be constituted by, for example, aset-top box (STB) connected with a digital interface such asHigh-Definition Multimedia Interface (HDMI) and a monitor. Note that“HDMI” is a registered trademark.

In addition, the example in which the container is an MPEG-2 TS (anMPEG-2 transport stream) or a transport stream of MPEG Media Transport(MMT) has been introduced in the above-described embodiment. However, acontainer to which the present technology can be applied is not limitedthereto, and a container in another format such as MP4 may be used.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

Additionally, the present technology may also be configured as below.

(1)

A transmission device including:

-   -   a transmission unit that transmits a container in a        predetermined format including a first component stream that        has, as component data, transmission video data obtained by        switching between a plurality of types of transmission video        data, and a predetermined number of second component streams        that have pieces of other component data; and    -   an information insertion unit that inserts dynamic range        information of the component data that each of the component        streams has into the component streams.

(2)

The transmission device according to (1),

-   -   wherein the information insertion unit further inserts color        gamut information of the component data that each of the        component streams has into the component streams.

(3)

The transmission device according to (1) or (2), further including:

-   -   another information insertion unit that inserts identification        information indicating a type of transmission video data that        the first component stream included in the container has into a        layer of the container so that the identification information        indicates a type of the transmission video data after the        switching from a timing a predetermined amount of time or more        earlier than a switching timing.

(4)

The transmission device according to any of (1) to (3),

-   -   wherein the predetermined number of second component streams        include a data broadcasting stream and/or a subtitle stream.

(5)

A transmission method including:

-   -   transmitting, by a transmission unit, a container in a        predetermined format including a first component stream that        has, as component data, transmission video data obtained by        switching between a plurality of types of transmission video        data, and a predetermined number of second component streams        that have pieces of other component data; and    -   inserting dynamic range information of the component data that        each of the component streams has into the component streams.

(6)

A reception device including:

-   -   a reception unit that receives a container in a predetermined        format including a first component stream that has, as component        data, transmission video data obtained by switching between a        plurality of types of transmission video data, and a        predetermined number of second component streams that have        pieces of other component data; and    -   a processing unit that obtains output data by decoding each of        the component streams, thus obtaining a plurality of pieces of        component data, and then performing compositing of the obtained        plurality of pieces of component data,    -   wherein dynamic range information of the component data that        each of the component streams has is inserted into the component        streams, and    -   the processing unit obtains the output data by performing a        luminance mapping process on each piece of the component data        based on the dynamic range information of each piece of the        component data to match display performance, and then performing        compositing of the component data.

(7)

The reception device according to (6),

-   -   wherein color gamut information of the component data that each        of the component streams has is inserted into the component        streams, and    -   the processing unit obtains the output data by performing a        color gamut conversion process on each piece of the component        data based on the color gamut information of each piece of the        component data to match display performance, and then performing        compositing of the component data.

(8)

A reception method including:

-   -   receiving, by a reception unit, a container in a predetermined        format including a first component stream that has, as component        data, transmission video data obtained by switching between a        plurality of types of transmission video data, and a        predetermined number of second component streams that have        pieces of other component data; and obtaining output data by        decoding each of the component streams, thus obtaining a        plurality of pieces of component data, and then performing        compositing of the obtained plurality of pieces of component        data,    -   wherein dynamic range information of the component data that        each of the component streams has is inserted into the component        streams, and    -   the output data is obtained in the processing by performing a        luminance mapping process on each piece of the component data        based on the dynamic range information of each piece of the        component data to match display performance, and then performing        compositing of the component data.

(9)

A transmission device including:

-   -   circuitry configured to        -   transmit information in a predetermined format that includes        -   a first component stream that has, as component data, video            data obtained by switching between a plurality of types of            video data, and        -   at least one second component stream that includes other            component data; and        -   insert dynamic range information of the component data into            the first component stream and insert dynamic range            information of the other component data into respective of            the at least one second component stream.

(10)

The transmission device according to (9),

-   -   wherein the information is a container in the predetermined        format.

(11)

The transmission device according to (10),

-   -   wherein the container in the predetermined format is a MPEG-2        transport stream(TS) or a transport stream of MPEG Media        Transport(MMT).

(12)

The transmission device according to (11),

-   -   wherein the circuitry is further configured to insert color        gamut information of the component data into the first component        stream and insert color gamut information of the other component        data into respective of the at least one second component        stream.

(13)

The transmission device according to (11), wherein

-   -   the circuitry is further configured to insert identification        information in the first component stream, the identification        information included at a position in the first component stream        that occurs at a predetermined amount of time prior to a        switching event, and the identification information identifies a        type of video data that is included in the first component        stream after the switching event, the switching event switches        one type of video data to another.

(14)

The transmission device according to (11),

-   -   wherein the at least one second component stream includes a data        broadcasting stream and/or a subtitle stream.

(15)

A transmission method including

-   -   transmitting, by a transmitter, information in a predetermined        format that includes a first component stream that has, as        component data, video data obtained by switching between a        plurality of types of video data, and    -   at least one second component stream that includes other        component data; and    -   inserting with circuitry dynamic range information of the        component data into the first component stream and inserting        dynamic range information of the other component data into        respective of the at least one second component stream.

(16)

A reception device including

-   -   a receiver configured to receive information in a predetermined        format that includes    -   a first component stream that has, as component data, video data        obtained by switching between a plurality of types of video        data, and,    -   at least one second component stream that includes other        component data; and    -   circuitry configured to decode the first component stream and        the at least one second component stream to obtain output data,        wherein the circuitry is configured to obtain from the first        component stream dynamic range information of the component data        and obtain from the other component data other dynamic range        information of the at least one second component stream, and    -   perform a luminance mapping process on the component data based        on the dynamic range information of the component data and based        on the other dynamic range information of the other component        data to match display performance, and obtain the output data by        combining respective outputs of the luminance mapping process.

(17)

The reception device according to (16), further including

-   -   a display configured to display an image associated with the        output data.

(18)

The reception device according to (16), wherein

-   -   color gamut information of the component data is included in the        first component stream and other color gamut information is        included in the at least one second component stream, and    -   the circuitry is configured perform a color gamut conversion        process based on the color gamut information and the other color        gamut information to match display performance, and then obtain        the output data by combining the component data and the other        component data.

(19)

A reception method including:

-   -   receiving, with a receiver, information in a predetermined        format that includes a first component stream that has, as        component data, video data obtained by switching between a        plurality of types of video data, and,    -   at least one second component stream that includes other        component data; and    -   decoding the first component stream and the at least one second        component stream to obtain output data,    -   the decoding including obtaining from the first component stream        dynamic range information of the component data and obtaining        from the other component data other dynamic range information        from the at least one second component stream, and    -   performing a luminance mapping process on the component data        based on the dynamic range information of the component data and        based on the other component data of the other dynamic range        information to match display performance, and obtaining the        output data by combining respective outputs of the luminance        mapping process.

A major characteristic of the present technology is that dynamic rangeinformation of component data that each of component streams has isinserted into the component streams and transmitted, thereby a receptionside can fix a characteristic of an electro-optical transfer, and thusoccurrence of an image disturbance caused by switching of theelectro-optical transfer characteristic can be prevented (see FIG. 2).

REFERENCE SIGNS LIST

10 transmission and reception system

100 service transmission system

101 control unit

102 video encoder

103 data service encoder

104 still image encoder

105 subtitle encoder

106 container encoder

107 transmission unit

200 service reception device

201 control unit

202 reception unit

203 container decoder

204 video decoder

205 data service decoder

206 still image decoder

207 subtitle decoder

208 OSD unit

209 screen composition processing unit

210 monitor

211 a, 211 b, 211 c, 211 d color gamut conversion unit

212 a, 212 b, 212 c, 212 d luminance mapping unit

213 compositing unit

214 HDR electro-optical transfer unit

221 electro-optical transfer unit (EOTF unit)

222 opto-electrical transfer unit (OETF unit)

231 SDR electro-optical transfer unit

232 HDR opto-electrical transfer unit

241 HDR1 electro-optical transfer unit

242 HDR2 opto-electrical transfer unit

251 HDR electro-optical transfer unit

252 SDR opto-electrical transfer unit

1. A transmission device comprising: circuitry configured to transmitinformation in a predetermined format that includes a first componentstream that has, as component data, video data obtained by switchingbetween a plurality of types of video data, and at least one secondcomponent stream that includes other component data; and insert dynamicrange information of the component data into the first component streamand insert dynamic range information of the other component data intorespective of the at least one second component stream.
 2. Thetransmission device according to claim 1, wherein the information is acontainer in the predetermined format.
 3. The transmission deviceaccording to claim 2, wherein the container in the predetermined formatis a MPEG-2 transport stream(TS) or a transport stream of MPEG MediaTransport(MMT).
 4. The transmission device according to claim 1, whereinthe circuitry is further configured to insert color gamut information ofthe component data into the first component stream and insert colorgamut information of the other component data into respective of the atleast one second component stream.
 5. The transmission device accordingto claim 1, wherein the circuitry is further configured to insertidentification information in the first component stream, theidentification information included at a position in the first componentstream that occurs at a pre-determined amount of time prior to aswitching event, and the identification information identifies a type ofvideo data that is included in the first component stream after theswitching event, the switching event switches one type of video data toanother.
 6. The transmission device according to claim 1, wherein the atleast one second component stream includes a data broadcasting streamand/or a subtitle stream.
 7. A transmission method comprising:transmitting, by a transmitter, information in a predetermined formatthat includes a first component stream that has, as component data,video data obtained by switching between a plurality of types of videodata, and at least one second component stream that includes othercomponent data; and inserting with circuitry dynamic range informationof the component data into the first component stream and insertingdynamic range information of the other component data into respective ofthe at least one second component stream.
 8. A reception devicecomprising: a receiver configured to receive information in apredetermined format that includes a first component stream that has, ascomponent data, video data obtained by switching between a plurality oftypes of video data, and, at least one second component stream thatincludes other component data; and circuitry configured to decode thefirst component stream and the at least one second component stream toobtain output data, wherein the circuitry is configured to obtain fromthe first component stream dynamic range information of the componentdata and obtain from the other component data other dynamic rangeinformation of the at least one second component stream, and perform aluminance mapping process on the component data based on the dynamicrange information of the component data and based on the other dynamicrange information of the other component data to match displayperformance, and obtain the output data by combining respective outputsof the luminance mapping process.
 9. The reception device according toclaim 8, further comprising: a display configured to display an imageassociated with the output data.
 10. The reception device according toclaim 8, wherein color gamut information of the component data isincluded in the first component stream and other color gamut informationis included in the at least one second component stream, and thecircuitry is configured perform a color gamut conversion process basedon the color gamut information and the other color gamut information tomatch display performance, and then obtain the output data by combiningthe component data and the other component data.
 11. A reception methodcomprising: receiving, with a receiver, information in a predeterminedformat that includes a first component stream that has, as componentdata, video data obtained by switching between a plurality of types ofvideo data, and, at least one second component stream that includesother component data; and decoding the first component stream and the atleast one second component stream to obtain output data, the decodingincluding obtaining from the first component stream dynamic rangeinformation of the component data and obtaining from the other componentdata other dynamic range information from the at least one secondcomponent stream, and performing a luminance mapping process on thecomponent data based on the dynamic range information of the componentdata and based on the other component data of the other dynamic rangeinformation to match display performance, and obtaining the output databy combining respective outputs of the luminance mapping process.